In the Long Term Evolution (LTE) and earlier wireless communication systems, there is only one carrier with a bandwidth up to 20 MHz in a cell as illustrated in FIG. 1. In the Long Term Evolution-Advanced (LTE-A) system, there are required peak rates of the system, up to 1 Gbps in the downlink and 500 Mbps in the uplink, as improved significantly over the LTE system. The required peak rates cannot be available with only one carrier with a bandwidth up to 20 MHz. Thus the technology of Carrier Aggregation (CA) has been introduced to the LTE-A system, where a plurality of consecutive or inconsecutive carriers served by the same evolved Node B (eNB) are aggregated together to serve a User Equipment (UE) concurrently as illustrated in FIG. 2. These carriers aggregated together are referred to as Component Carriers (CCs). Each cell can be a component carrier, and cells (component carriers) served by different eNBs cannot be aggregated. In order to ensure backward compatibility with a UE in the LTE system, the bandwidth of each of the carriers should be no more than 20 MHz.
One of the component carriers aggregated for the UE is defined as a Primary Component Carrier (PCC) including a downlink PCC and an uplink PCC, and the remaining component carriers are referred to as Secondary Component Carriers (SCCs).
In the LTE-A Release 10 (Rel-10), each of the component carriers aggregated for the UE corresponds to maximum transmit power PCMAX,c of the carrier, and the maximum transmit power of the carrier lies in the range of values of PCMAX_L,c≦PCMAX,c≦PCMAX_H,c, where PCMAX_L,c and PCMAX_H,c are determined by the UE as follows:
In the case of intra-band CA:PCMAX_L,c=MIN{PEMAX,c−TC,c,PPowerClass−MAX(MPRc+A-MPRc,P-MPRc)−TC,c};  Equation 1:andPCMAX_H,c=MIN{PEMAX,c,PPowerClass};  Equation 2:
In the case of inter-band CA:andMIN{PEMAX,c−TC,c,PPowerClass−MAX(MPRc+A-MPRc+TB,c,P-MPRc)−TC,c};  Equation 3:PCMAX_H,c=MIN{PEMAX,c,PPowerClass};  Equation 4:
Where PEMAX,c represents allowable maximum power configured by the network side for the respective component carrier, PPowerClass represents a UE power level, related to a band in which the UE transmits, without taking into account any power reduction, P-MPR (Power Management Maximum Power Reduction) represents a predefined maximum power reduction, TC,c=1.5 dB or 0 represents a sideband transmit power reduction corresponding to the respective component carrier; MPRc (Maximum Power Reduction) and A-MPRc (Additional-Maximum Power Reduction) represent power reductions, corresponding to the respective component carrier, related to a transmit bandwidth, a modulation order, particular Resource Block (RB) allocation, etc.; and TIB,c represents an additional sideband reduction; and
In the case of intra-band CA, both MPRc and A-MPRc are the same for each component carrier and are determined according to the sum of transmit bandwidths of uplink channels and uplink signals concurrently transmitted on the respective aggregated component carriers, and if there are a plurality of modulation modes, then the modulation mode at the highest order may apply. In the case of inter-band CA, if the respective aggregated component carriers lie in different separate bands, and the power reduction parameter of the respective component carrier is determined only according to the sum of transmit bandwidths of an uplink channel and an uplink signal concurrently transmitted on the component carrier, then MPRc of the respective component carriers may be different from each other, and also A-MPRc of the respective component carriers may be different from each other, and if there are a plurality of modulation modes, then the modulation mode at the highest order may apply.
Unlike the LTE system, the following several characteristics are supported in the LTE-A system: a Physical Uplink Shared Channel (PUSCH) is transmitted on a component carrier by allocating inconsecutive resources; both a PUSCH and a Physical Uplink Control Channel (PUCCH) are transmitted concurrently on the PCC; both a PUSCH and a PUCCH on different component carriers are transmitted concurrently; and PUSCHs on different component carriers are transmitted concurrently.
Power Headroom (PH) reported by the UE is primarily used by the eNB to determine remaining power of the UE to thereby schedule reasonably the PUSCH to be transmitted in a larger number of Physical Resource Blocks (PRBs) without being limited in power. Thus power reduction conditions of the respective component carriers may be different from each other due to the transmission characteristics above in the LTE-A system, so PHs corresponding to respective component carriers need to be reported so that the eNB schedules more reasonably uplink transmission on the component carriers. Moreover the PHs should not only reflect a power headroom when the PUSCH is transmitted, but also reflect a power headroom when both the PUCCH and the PUSCH are transmitted, so the following two PH report types are defined in the LTE-A Rel-10 system:
Firstly the Type 1 PH primarily reflects the power headroom when the PUSCH is transmitted, which will be reported for each component carrier.
Secondly the Type 2 PH primarily reflects the power headroom when both the PUCCH and the PUSCH are transmitted, which will be reported only for the PCC.
There are three duplex modes supported in the LTE system: the Frequency Division Duplex (FDD) mode as illustrated in FIG. 3A, the Half-Frequency Division Duplex (H-FDD) mode as illustrated in FIG. 3B, and the Time Division Duplex (TDD) mode as illustrated in FIG. 3C. Here the FDD refers to that uplink transmission and downlink transmission are performed in different carrier frequency bands so that both the base station and the user equipment can receive a signal and transmit a signal concurrently. To this end, the FDD devices need to be provided with two sets of transceivers and duplex filters. The H-FDD differs from the FDD in that the user equipment cannot transmit a signal and receive a signal concurrently, that is, the base station in the H-FDD is the same as the base station in the FDD, but the user equipment in the H-FDD can be simplified relative to the user equipment in the FDD by maintaining only one of the sets of transceivers and saving a cost of the duplexer. The TDD refers to that uplink transmission and downlink transmission are performed in the same carrier frequency band to enable transmission (reception) or reception (transmission) of a channel by the base station (user equipment) respectively in different periods of time.
It is very likely to support carrier aggregation of an FDD carrier and a TDD carrier in evolved systems subsequent to the LTE-A system, and at this time the UE may support transmission of the PUCCHs on different uplink carriers corresponding to different sets of carriers, and both the PUCCH and the PUSCH may be transmitted on a plurality of uplink carriers, but there has been absent so far a corresponding PH report solution in this scenario.